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Estrogens and selective estrogen receptor modulators differentially antagonize Runx2 in ST2 mesenchymal progenitor cells.

ABSTRACT: Estrogens attenuate bone turnover by inhibiting both osteoclasts and osteoblasts, in part through antagonizing Runx2. Apparently conflicting, stimulatory effects in osteoblast lineage cells, however, sway the balance between bone resorption and bone formation in favor of the latter. Consistent with this dualism, 17ß-estradiol (E2) both stimulates and inhibits Runx2 in a locus-specific manner, and here we provide evidence for such locus-specific regulation of Runx2 by E2 in vivo. We also demonstrate dual, negative and positive, regulation of Runx2-driven alkaline phosphatase (ALP) activity by increasing E2 concentrations in ST2 osteoblast progenitor cells. We further compared the effects of E2 to those of the Selective Estrogen Receptor Modulators (SERMs) raloxifene (ral) and lasofoxifene (las) and the phytoestrogen puerarin. We found that E2 at the physiological concentrations of 0.1-1?nM, as well as ral and las, but not puerarin, antagonize Runx2-driven ALP activity. At ?10?nM, E2 and puerarin, but not ral or las, stimulate ALP relative to the activity measured at 0.1-1?nM. Contrasting the difference between E2 and SERMs in ST2 cells, they all shared a similar dose-response profile when inhibiting pre-osteoclast proliferation. That ral and las poorly mimic the locus- and concentration-dependent effects of E2 in mesenchymal progenitor cells may help explain their limited clinical efficacy.

SUBMITTER: Amzaleg Y

PROVIDER: S-EPMC6128776 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Estrogens and selective estrogen receptor modulators differentially antagonize Runx2 in ST2 mesenchymal progenitor cells.

Amzaleg Yonatan Y Ji Jie J Kittivanichkul Donlaporn D E Törnqvist Anna A Windahl Sara S Sabag Elias E Khalid Aysha B AB Sternberg Hal H West Michael M Katzenellenbogen John A JA Krum Susan A SA Chimge Nyam-Osor NO Schones Dustin E DE Gabet Yankel Y Ohlsson Claes C Frenkel Baruch B

The Journal of steroid biochemistry and molecular biology 20180508

Estrogens attenuate bone turnover by inhibiting both osteoclasts and osteoblasts, in part through antagonizing Runx2. Apparently conflicting, stimulatory effects in osteoblast lineage cells, however, sway the balance between bone resorption and bone formation in favor of the latter. Consistent with this dualism, 17ß-estradiol (E2) both stimulates and inhibits Runx2 in a locus-specific manner, and here we provide evidence for such locus-specific regulation of Runx2 by E2 in vivo. We also demonstr ...[more]

PMID: 29751107

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Project description:UnlabelledWe profiled the global gene expression of a bone marrow-derived mesenchymal pluripotent cell line in response to Runx2 expression. Besides osteoblast differentiation, Runx2 promoted the osteoclastogenesis of co-cultured splenocytes. This was attributable to the upregulation of many novel osteoclastogenic genes and the downregulation of anti-osteoclastogenic genes.IntroductionIn addition to being a master regulator for osteoblast differentiation, Runx2 controls osteoblast-driven osteoclastogenesis. Previous studies profiling gene expression during osteoblast differentiation had limited focus on Runx2 or paid little attention to its role in mediating osteoblast-driven osteoclastogenesis.MethodsST2/Rx2(dox), a bone marrow-derived mesenchymal pluripotent cell line that expresses Runx2 in response to Doxycycline (Dox), was used to profile Runx2-induced gene expression changes. Runx2-induced osteoblast differentiation was assessed based on alkaline phosphatase staining and expression of classical marker genes. Osteoclastogenic potential was evaluated by TRAP staining of osteoclasts that differentiated from primary murine splenocytes co-cultured with the ST2/Rx2(dox) cells. The BeadChip™ platform (Illumina) was used to interrogate genome-wide expression changes in ST2/Rx2(dox) cultures after treatment with Dox or vehicle for 24 or 48 h. Expression of selected genes was also measured by RT-qPCR.ResultsDox-mediated Runx2 induction in ST2 cells stimulated their own differentiation along the osteoblast lineage and the differentiation of co-cultured splenocytes into osteoclasts. The latter was attributable to the stimulation of osteoclastogenic genes such as Sema7a, Ltc4s, Efnb1, Apcdd1, and Tnc as well as the inhibition of anti-osteoclastogenic genes such as Tnfrsf11b (OPG), Sema3a, Slco2b1, Ogn, Clec2d (Ocil), Il1rn, and Rspo2.ConclusionDirect control of osteoblast differentiation and concomitant indirect control of osteoclast differentiation, both through the activity of Runx2 in pre-osteoblasts, constitute a novel mechanism of coordination with a potential crucial role in coupling bone formation and resorption.

Project description:In addition to its thoroughly investigated role in bone formation, the osteoblast master transcription factor RUNX2 also promotes osteoclastogenesis and bone resorption. Here we demonstrate that 17β-estradiol (E2), strongly inhibits RUNX2-mediated osteoblast-driven osteoclastogenesis in co-cultures. Towards deciphering the underlying mechanism, we induced premature expression of RUNX2 in primary murine pre-osteoblasts, which resulted in robust differentiation of co-cultured splenocytes into mature osteoclasts. This was attributable to RUNX2-mediated increase in RANKL secretion, determined by ELISA, as well as to RUNX2-mediated increase in RANKL association with the osteoblast membrane, demonstrated using confocal fluorescence microscopy. The increased association with the osteoblast membrane was recapitulated by transiently expressed GFP-RANKL. E2 abolished the RUNX2-mediated increase in membrane-associated RANKL and GFP-RANKL, as well as the concomitant osteoclastogenesis. RUNX2-mediated RANKL cellular redistribution was attributable in part to a decrease in Opg expression, but E2 did not influence Opg expression either in the presence or absence of RUNX2. Diminution of RUNX2-mediated osteoclastogenesis by E2 occurred regardless of whether the pre-osteoclasts were derived from wild type or estrogen receptor alpha (ERα)-knockout mice, suggesting that activated ERα inhibited osteoblast-driven osteoclastogenesis by acting in osteoblasts, possibly targeting RUNX2. Indeed, microarray analysis demonstrated global attenuation of the RUNX2 response by E2, including abrogation of Pstpip2 expression, which likely plays a critical role in membrane trafficking. Finally, the selective ER modulators (SERMs) tamoxifen and raloxifene mimicked E2 in abrogating the stimulatory effect of osteoblastic RUNX2 on osteoclast differentiation in the co-culture assay. Thus, E2 antagonizes RUNX2-mediated RANKL trafficking and subsequent osteoclastogenesis. Targeting RUNX2 and/or downstream mechanisms that regulate RANKL trafficking may lead to the development of improved SERMs and possibly non-hormonal therapeutic approaches to high turnover bone disease.

Project description:Estrogen is a reproductive steroid hormone that has both beneficial and detrimental effects on the cardiovascular system. Selective estrogen receptor modulators (SERMs) exhibit partial estrogen agonist/antagonist activity in estrogen target tissues. Since we still have an incomplete picture of the gene targets of estrogen in the vasculature, and our understanding of SERM gene targets in the vasculature is even less well-developed, it is important to broaden the available information on this subject. The present study tested the hypothesis that estrogens (ethinyl estradiol, estradiol benzoate, and equilin) and SERMs (tamoxifen and raloxifene) cause differential gene and protein expression in the vasculature. DNA microarray and real-time RT-PCR were used to investigate gene expression in the mesenteric arteries of estrogen and SERM treated ovariectomized rats. The genes shown to be differentially expressed included stearoyl-CoA desaturase (SCD), soluble epoxide hydrolase (sEH), secreted frizzled related protein-4 (SFRP-4), insulin-like growth factor-1 (IGF-1), phospholipase A2 group 1B (PLA2-G1B), and fatty acid synthase (FAS). Western blot further confirmed the differential expression of sEH, SFRP-4, FAS, and SCD protein. These results reveal that estrogens and SERMs cause differential gene and protein expression in the mesenteric artery. Consequently, the use of these agents may be associated with a unique profile of functional and structural changes in the mesenteric arterial circulation. Goal of the experiment: To examine the effects of three formulations of estrogen (ethinyl estradiol, equilin, and estradiol benzoate) and of the selective estrogen receptor modulators, tamoxifen and raloxifene, on gene expression in the mesenteric arteries of the rat. Keywords: rat, artery, gene expression, mesentery, estrogen, tamoxifen, raloxifene Experimental factors: hormone treatment, drug treatment Experimental design: Prepubertal female Sprague Dawley rats (Harlan, Indianapolis, IN) were ovariectomized at 4 weeks of age, prior to the initiation of regular ovarian cycles. The animals were allowed to recover for 2 weeks before the experimental protocol was initiated. The rats were randomly divided into 6 groups (n=3-4/group) and treated by daily gavage for 3 weeks with the vehicle (20% 2-hydroxypropyl-β-cyclodextrin, Sigma, St Louis, MO), ethinyl estradiol (EE, 0.15 mg/kg; Sigma), estradiol benzoate (EB, 0.15 mg/kg; Sigma), equilin (EQ, 0.15 mg/kg; Sigma), tamoxifen (TAM, 3 mg/kg; Sigma), or raloxifene (RAL, 3 mg/kg; Eli Lilly & Co., Indianapolis, IN). After 3 weeks of treatment, the rats were euthanized and the mesentery obtained. Total RNA was extracted from each individual sample and used for the synthesis of labeled cRNA for microarray analysis. After the final gavage treatment on day 21, the rats were deeply anesthetized with isoflurane and euthanized by decapitation. The mesenteric arterial tree was isolated and harvested and stored in RNAlater (Ambion) at -80ºC. The mesenteric arteries were dissected free from veins and surrounding fat and homogenized in TRI reagent (MRC, Cincinnati, OH). Mesenteric artery RNA was extracted and purified using an RNeasy Mini Kit (Qiagen). Any potentially contaminating DNA was removed by treatment with RNase-free DNase (Qiagen) on the RNeasy column. Total RNA was quantified and RNA integrity was assessed using the Agilent Bioanalyzer (Santa Clara, CA). Following analysis, the RNA was stored at -80ºC until it was used for gene expression studies. DNA microarray: CodeLink Whole Rat Genome Bioarrays (Applied Microarrays, Tempe, AZ) were used. Five μg total RNA was used from each mesenteric arterial sample for the microarray analysis. Complementary RNA was synthesized per company protocol (Ambion). A set of bacterial RNAs was added to each total RNA sample and carried through the synthesis and labeling reactions as controls and for nor¬malization of the data. The microarrays were scanned with the GenePix 4000B (Axon Instruments, Union City, CA) with GenePix Pro 5.0 software (Axon Instruments). Analysis of the microar¬rays was performed with the CodeLink Expression Analysis software (Applied Microarrays) and Acuity 3.1 software (Axon), and statistical analysis was performed with GeneSpring 7.1 software (Agilent, Santa Clara, CA). A sample of n=3 was completed with the microarrays for each treatment. Quality control steps: The cRNA that was synthesized from each mesenteric artery treatment sample was used for hybridization to a single CodeLink (Applied Microarrays) whole rat genome microarray. Only one sample was hybridized with each slide and only one dye (streptavidin-Alexa 647) was used so no dye swaps were used. Bacterial control spikes were used per manufacturer's instructions. Samples used, extract preparation and labeling: The origin of each biological sample: The samples were isolated mesenteric arteries from individual Sprague Dawley rats that had been treated by daily gavage for 3 weeks with the vehicle (20% 2-hydroxypropyl-β-cyclodextrin, Sigma, St Louis, MO), ethinyl estradiol (EE, 0.15 mg/kg; Sigma), estradiol benzoate (EB, 0.15 mg/kg; Sigma), equilin (EQ, 0.15 mg/kg; Sigma), tamoxifen (TAM, 3 mg/kg; Sigma), or raloxifene (RAL, 3 mg/kg; Eli Lilly & Co., Indianapolis, IN). Manipulations of biological samples and protocols used: Ovariectomized female rats were treated by daily gavage for 3 weeks with the vehicle (20% 2-hydroxypropyl-β-cyclodextrin, Sigma, St Louis, MO), ethinyl estradiol (EE, 0.15 mg/kg; Sigma), estradiol benzoate (EB, 0.15 mg/kg; Sigma), equilin (EQ, 0.15 mg/kg; Sigma), tamoxifen (TAM, 3 mg/kg; Sigma), or raloxifene (RAL, 3 mg/kg; Eli Lilly & Co., Indianapolis, IN). After the final gavage treatment on day 21, the rats were deeply anesthetized with isoflurane and euthanized by decapitation. The mesenteric arterial tree was isolated, harvested, and stored in RNAlater (Ambion) at -80ºC. The mesenteric arteries were dissected free from veins and surrounding fat and homogenized in TRI reagent (MRC, Cincinnati, OH). Experimental factor: hormone treatment, drug treatment Technical protocols: The mesenteric arteries were minced with scalpels and TRI reagent (MRC) was added. The tissue was homogenized with a Polytron homogenizer. Bromochloropropane and sodium acetate were added, and the samples were centrifuged to separate the phases. The RNA-containing layer was removed and the RNA purified on an RNeasy extraction column (Qiagen). The sample was treated with an on-column DNase treatment (RNase-free DNase, Qiagen). The purity and quantity were evaluated by an Agilent Bioanalyzer using the RNA 6000 Nanoassay LabChip. Labeled cRNA was prepared using the Message Amp II-Biotin Enhanced Kit from Ambion, following the manufacturer's Instruction Protocol. 5.0 microgram of rat mesenteric artery total RNA was mixed with bacterial control RNA spikes and primed with T7 oligo(dT) primer for 10 min at 70C. (The bacterial control spikes included araB, entF, fixB, gnd, hisB, and leuB.) The first strand of cDNA was synthesized with first strand buffer, dNTP mix, RNase inhibitor, and reverse transcriptase for 2 h at 42C. The second strand cDNA synthesis reaction was prepared using second strand buffer, dNTP mix, DNA polymerase mix, and RNase H; the reaction was carried out for 2h at 16C. The double-stranded cDNA was purified on spin columns included in the Ambion kit. The double-stranded cDNA was mixed with T7 reaction buffer, T7 ATP, T7 GTP, T7 UTP, T7 CTP, biotin-11-UTP, and T7 enzyme mix for the synthesis of cRNA. The cRNA synthesis reaction was terminated after 14h at 37C by purifying the cRNA on spin columns from the Ambion kit. The concentration of cRNA was determined by spectrophotometry. Hybridization procedures and parameters: 10 micrograms of biotinylated cRNA was mixed with fragmentation buffer and heated to 94C for 20 min. The fragmented cRNA was mixed with CodeLink hybridization buffer, loaded on the microarray slides (CodeLink Whole Rat Genome Bioarrays), and hybridized for 18 hours at 37C. The slides were washed in 0.75x TNT (Tris-HCl, NaCl, Tween-20) at 46C for 1h then incubated with streptavidin-Alexa 647 fluorescent dye for 30 min at room temperature. The streptavidin-Alexa 647 fluor was prepared in TNB blocking buffer (0.1M Tris-HCl, 0.15M NaCL, 0.5% NEN Blocking Reagent-PerkinElmer) The slides were then washed 4 times for 5 min each in 1x TNT and twice in 0.05% Tween 20 for 5 sec each. The slides were dried by centrifugation and scanned in an Axon GenePix 4000B scanner.

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Estrogens and selective estrogen receptor modulators differentially antagonize Runx2 in ST2 mesenchymal progenitor cells.

Publications

Estrogens and selective estrogen receptor modulators differentially antagonize Runx2 in ST2 mesenchymal progenitor cells.

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